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Underwater GPS for Ship navigation

(Bo Koppel) #1

On larger ROV/position systems You can use USBL for “follow sub” mode.
That means the ship is following the sub/ROV automatic, or manual.

A way to do this with more moderate budgets could be software integration with ship existing navigation systems.
A standard way for position input into navigation systems is AIS Surface targetting.
Many computer based navigation systems have possibility to input NMEA AIS sentences.
Could be via virtual COM ports through TCP/IP or UDP.
That means they could be merged with Surface AIS.
Software could be open source “OpenCPN” or others.
By that way You could set up survey route and navigation in helms position, together with ROV actual position.

So: Is there a future way in “Underwater GPS” to send actual ROV position as AIS to other computers?
/ Bo

(Jacob) #2

We don’t have any plans for this at the moment, but it sounds like it should be possible.

(Oystein Skarholm) #3

To have the vessel in a ROV follow mode you will need enough propellers to allow the vessel to move in x/y axis while still maintaining best heading. If not i think the drift-off would be to large. I cannot see that a single prop vessel will be able to achieve this.

(Bo Koppel) #4

Thanks for input!
Ship spec is of course important and project related.
We, and others, do similar solutions today with Tritech and Kongsberg positioning.
Question is if BlueRobotics/Waterlinked is considering future entering this segment.
That could make cost revolution like the BlueROV has already done, and that UWGPS might follow.

(Roy Petter Dyrdahl Torgersen) #5

So the main limitation here is not related to BR/WL technology. The current solution will already provide distance and bearing to target, which you could follow by manual use of onboard propulsion systems. You could most likely also interface this info with your electronic chart system of choice.

But in order to automatically “follow sub”, you will need a DP-capable vessel, most importantly when it comes to truster configuration, but also sensor inputs and onboard control system. This is highly complex and costly, and as @SDI points out you can’t easily retrofit existing boats. Even a very basic boat would need, for DP 0, at least the following:

  • Sufficient thrusters for 3 DOF (i.e. bow & stern thruster + main prop or 2 main props + bow thruster)
  • Computer capable of running the control software
  • Human Machine Interface (Could maybe run on the same computer as above, but is normally separated)
  • GPS for position reference (pref. Differential)
  • A very good heading indicator (pref. Gyro Compass but Fluxgate or similar could also be used)
  • A Motion Reference Unit or IMU in order to compensate for ships movements on GPS

And if you want to offer this boat for charter, you would most likely be asked to provide redundancy of all these components.

Having said that, bearing in mind the recent crisis in O&G, and all the new developments happening in offshore wind and aquaculture, asset owners have become much more cost conscious, so there might be room for a tiny inspection vessel using a DP0 / WL / BROV2 combo. Or they might just continue to press prices with current shipowners.

(Bo Koppel) #6

I am apparently doing a bad job explaining what we want in the future.
So I try again.
We work today on ships ranging from 100 meter DP2 vessels to smaller manual station holding setups.
These ships works perfect for the projects today, so this is not about ship handling/spec.
I think Waterlinked/BlueROV can take some of these projects in the future.
Ship following the ROV today is done with expensive positioning systems.

Moderate budget projects is done two ways today:
-Either with DP officer manually following the positioning from ROV on Bridge systems by manual DP input.
-Or a basic manual station holding where bridge handle the ship manually, also from ROV positioning.

To do this with BlueROV/Waterlinked I can see two ways that would be on a revolutionary budget.
That could motivate us and others to invest in systems.
Seems technically easy softwarewise on the BlueROV/Waterlinked end.

First stage would be manual handling of the ship.
Here the bridge must have the real World (GPS related) position of the ROV in graphics.

This could in my mind be done two ways the Waterlinked way.

  1. Sending position in a format that different ship bridgesystems can handle.
    One basic way of that, that exist today, is importing AIS NMEA strings with ROV position.
    These positions will by that be overlayed on one navigation display on bridge.
    Easiest way for that I think is by sending by UDP or TCP

  2. Stand alone webUI or other graphic interface on bridge on a separate display.
    That means showing the Waterlinked part of QGC on another computer, at the same time as on ROV control.
    This way I think the position should be sent over extended ROV Ethernet to bridge.
    / Bo

(Jacob) #7

@Boko very nice ideas, both 1 and 2 are possible. 2 can be done right now.

(Bo Koppel) #8

Nice with second graphic interface for positioning working already as my point #2!
Is that as simple as running one more computer with QGC, or are You having other thoughts?

Regarding Waterlinked, I read in “BR add on manual” that GPS position is fixed only for the moment.
Is this still the case? If so, is it possible to have a hands up or so in forum or website when it works?
/ Bo

(Jacob) #9

They just updated to enable this. I will update our docs now, thank you for the heads up :).

You can run a second computer with IP You can either use QGC to view (turn off heartbeats on the second computer), or Water Linked’s web interface (demo).

(Roy Petter Dyrdahl Torgersen) #10

Yeah so as pointed out, option 2 is already available. I suppose you’ve seen the videos on the Blue Robotics Youtube channel?
If you haven’t seen it already, I think the following video might be of particular interest to you:

You might be aware of this already, but in any case, here’s a word of caution: AIS is an official radio system that transmit data over VHF links. Although it might seem relatively easy to go out and by a “Type B” AIS tx/rx box, the actual regulatory & legal stuff behind it is very complex. I would strongly discourage any sort of tampering with AIS, as you might end up getting your National Coast Guard on your back, and heavy fines to go with it. Just as a recommendation.

With regards to your project plan, the manual control part is straight forward. Your work capabilities are going to depend on 2 things only: your OOWs ship handling capabilities and your ships power plant.

But if you want to go automatic, that’s where my previous post comes in.


TeamViewer is another easy way to share the screen with QGC. But it would be nice if position, depth and heading, could be exported as NMEA on either a com port or udp/tcp.

(Bo Koppel) #12

That is a working idea!
Also tested VNC for similar solution of distributing existing screen capture live.
Still, we prefer live display in positioning display.

(Jacob) #13

Let me know which sentences you want, and I can do it at some point.


When DeepVision is ready with their sidescan for BR2, I think that GGA, RMC, with altitude as depth, would do the trick.